The study compared people born during and after sugar rationing in the United Kingdom during World War II.
People exposed to less sugar before birth and during their first one to two years of life were less likely to develop dementia decades later, according to an observational study of nearly 65,000 people. They also tended to receive a dementia diagnosis later in life, although the findings do not prove that consuming less sugar directly prevents the disease.
The study, published in Neurology, used an unusual period in British history to investigate the relationship. Researchers compared 64,737 people born around World War II sugar rationing in the United Kingdom, when access to sugar was restricted before becoming widely available again in 1953.
“Our findings suggest that limiting sugar during the earliest stages of life may have lasting benefits for brain health,” said study author Jiazhen Zheng, PhD, of The Hong Kong University of Science and Technology in Guangzhou, China. “These results highlight the potential importance of early-life nutrition in reducing the risk of dementia decades later.”
Rationing created a natural comparison
The researchers divided participants according to how much of their earliest development coincided with sugar rationing. One group experienced rationing before birth and through the first year of life, another experienced it before birth and until age two, and a third was born after rationing had ended.
Beginning when participants were an average age of 55, the researchers examined medical records for dementia diagnoses over as many as 15 subsequent years.
Among 15,025 people exposed to rationing before birth and during their first year, 388 developed dementia. Of 15,256 who experienced rationing before birth and through their first two years, 456 were diagnosed. By comparison, dementia developed in 504 of the 23,774 participants born after sugar rationing.
Early sugar limits tracked with lower risk
After accounting for age, sex, and health conditions including high blood pressure and diabetes, the researchers found that exposure to sugar rationing before birth and through age one was associated with a 21% lower risk of dementia compared with being born after rationing ended.
For people whose exposure continued before birth through age two, the associated reduction in dementia risk was 23%.
Lower sugar levels during early life were also associated with dementia developing an average of 2.6 years later.
Brain imaging available for a smaller subset of participants provided another point of comparison. People who had lower sugar exposure early in life had greater total gray matter volume and fewer white matter hyperintensities, which are markers of damage to brain tissue.
“Limiting added sugars during pregnancy and infancy may be one beneficial step that families and communities can take, but further research is needed to better understand how these early exposures influence dementia risk and to guide public health strategies,” Zheng said.
The researchers cautioned that the study was observational and examined events that had occurred decades earlier rather than following participants prospectively over time. As a result, the findings establish an association between early sugar exposure and later dementia risk, not proof that reducing sugar directly prevents dementia.
Reference: “Association of Sugar Restriction in Utero Through Age 2 Years on Dementia Risk Later in Life” by Jiazhen Zheng, Gregory Y.H. Lip, Zhuoni Zhang and S. W. Ricky Lee, 29 July 2026, Neurology.
DOI: 10.1212/WNL.0000000000218313
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